I never saw it coming. I had been thinking all offseason how it wouldn't make any sense for him to retire after a great season.
But in some way that that makes the most sense in Favre-logic. He didn't retire after GM Ted Thompson came in and got rid of his head coach, veteran offensive line, star wide receiver, all his friends on the team, and failed to trade for WR Randy Moss after Thompson said he would. He didn't retire after most people thought he was done after watching him struggle in 2005 and 2006 with an inferior, and then young, offense. Now when everything has worked out and he's one step away from another Super Bowl, he's finally "mentally tired."
I hope he really means it. I don't want to watch a 40 year old Favre trying to catch the magic one more time on the Packers or some other team after he's stepped away from football for a year.
Obviously this changes the team. Luckily QB Aaron Rodgers looked good when given the chance in 2007, but he's as brittle as Favre is indestructible. There is nothing worth mentioning in the free agent market, although maybe a veteran QB with experience in Mike McCarthy's system like Todd Bouman would have some appeal as a 3rd QB who could be part player/part coach. This is a good draft for quarterbacks and they have to draft a quarterback who can challenge for the starting job and effectively fill-in after the inevitable Rodgers injury.